Properties of blood, porphyrins, and exposure to legacy and emerging persistent organic pollutants in surf scoters (Melanitta perspicillata) overwintering on the south coast of British Columbia, Canada.

Bottom Line:
In addition, a low proportion of lymphocytes in individuals across locations in early spring samples was associated with poor body condition.The apparent loss of fitness just prior to the onset of northerly migrations to breeding grounds is of particular concern.Compromised health of mature birds at this point in the season might impact negatively on the productivity and survival of some individuals, particularly those overwintering in Howe Sound.

ABSTRACTThe surf scoter (Melanitta perspicillata) is a little-studied species of North American sea duck. Estimates suggest it has experienced a precipitous decline in breeding numbers over the latter half of the past century. To investigate the potential role of contaminant uptake and toxicity in the population decline, this study undertook to measure blood chemistry, porphyrin concentrations, EROD, and organic contaminants in mature surf scoters wintering in the Strait of Georgia, BC, Canada. Hepatic organochlorine pesticide, polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran, polychlorinated biphenyl (PCB), polybrominated diphenyl ether, and nonylphenol concentrations were relatively low; for example, SigmaTEQs (toxic equivalents) for PCBs, dioxins, and furans combined ranged from 4.7 ng/kg wet weight in reference-site (Baynes Sound) birds to 11.4 ng/kg wet weight in birds from Vancouver Harbour. Nonetheless, elevated EROD activity indicated that birds in Howe Sound were responding to an Ah-receptor-mediated stressor, which was also affecting hematocrit values and possibly vitamin A status. In addition, a low proportion of lymphocytes in individuals across locations in early spring samples was associated with poor body condition. The apparent loss of fitness just prior to the onset of northerly migrations to breeding grounds is of particular concern. Compromised health of mature birds at this point in the season might impact negatively on the productivity and survival of some individuals, particularly those overwintering in Howe Sound.

Fig3: Geographic differences in the differential white blood cell counts of adult male surf scoters collected from three locations in the Strait of Georgia, BC, in early spring (February–March) 1999. Bars with different letters above them represent significantly different least squares mean values (p-Values are given in the Results section). Error bars represent upper and lower confidence intervals. Geometric mean values for adult males collected from Vancouver Harbour in spring 2001 are shown for comparison but were not included in the statistical evaluations

Mentions:
There was considerable seasonal and yearly variability in differential white blood cell counts, which precluded the pooling of data collected at different times. However, an assessment of adult males collected from three locations at one time, in the early spring of 1999, indicated that the proportional representation of lymphocytes was significantly lower (p = 0.01, n = 17) and heterophils significantly higher (p = 0.05, n = 17) in birds from the reference site, Baynes Sound, compared to those from Howe Sound (Fig. 3). A nonstatistical comparison of individuals collected from Vancouver Harbour 2 years later indicated that there was a far greater elevation of the heterophil:lymphocyte ratio in harbor-site birds at another point in time, apparent in both males and females (Fig. 3). In an assessment of all adult male surf scoters collected during the study, there were significant positive associations found between the prevalence of lymphocytes and both the total body mass (Pearson r = 0.636, p = 0.0005, n = 32) and the prevalence of parasites in the adrenal glands (Pearson r = 0.608, p = 0.001). This was largely due to coinciding relatively low lymphocyte proportions, low body mass, and low parasite incidence (0 to 1 on a rank-scale of 0 to 3) in males collected from Vancouver Harbour in February 2001.Fig. 3

Properties of blood, porphyrins, and exposure to legacy and emerging persistent organic pollutants in surf scoters (Melanitta perspicillata) overwintering on the south coast of British Columbia, Canada.

Fig3: Geographic differences in the differential white blood cell counts of adult male surf scoters collected from three locations in the Strait of Georgia, BC, in early spring (February–March) 1999. Bars with different letters above them represent significantly different least squares mean values (p-Values are given in the Results section). Error bars represent upper and lower confidence intervals. Geometric mean values for adult males collected from Vancouver Harbour in spring 2001 are shown for comparison but were not included in the statistical evaluations

Mentions:
There was considerable seasonal and yearly variability in differential white blood cell counts, which precluded the pooling of data collected at different times. However, an assessment of adult males collected from three locations at one time, in the early spring of 1999, indicated that the proportional representation of lymphocytes was significantly lower (p = 0.01, n = 17) and heterophils significantly higher (p = 0.05, n = 17) in birds from the reference site, Baynes Sound, compared to those from Howe Sound (Fig. 3). A nonstatistical comparison of individuals collected from Vancouver Harbour 2 years later indicated that there was a far greater elevation of the heterophil:lymphocyte ratio in harbor-site birds at another point in time, apparent in both males and females (Fig. 3). In an assessment of all adult male surf scoters collected during the study, there were significant positive associations found between the prevalence of lymphocytes and both the total body mass (Pearson r = 0.636, p = 0.0005, n = 32) and the prevalence of parasites in the adrenal glands (Pearson r = 0.608, p = 0.001). This was largely due to coinciding relatively low lymphocyte proportions, low body mass, and low parasite incidence (0 to 1 on a rank-scale of 0 to 3) in males collected from Vancouver Harbour in February 2001.Fig. 3

Bottom Line:
In addition, a low proportion of lymphocytes in individuals across locations in early spring samples was associated with poor body condition.The apparent loss of fitness just prior to the onset of northerly migrations to breeding grounds is of particular concern.Compromised health of mature birds at this point in the season might impact negatively on the productivity and survival of some individuals, particularly those overwintering in Howe Sound.

ABSTRACTThe surf scoter (Melanitta perspicillata) is a little-studied species of North American sea duck. Estimates suggest it has experienced a precipitous decline in breeding numbers over the latter half of the past century. To investigate the potential role of contaminant uptake and toxicity in the population decline, this study undertook to measure blood chemistry, porphyrin concentrations, EROD, and organic contaminants in mature surf scoters wintering in the Strait of Georgia, BC, Canada. Hepatic organochlorine pesticide, polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran, polychlorinated biphenyl (PCB), polybrominated diphenyl ether, and nonylphenol concentrations were relatively low; for example, SigmaTEQs (toxic equivalents) for PCBs, dioxins, and furans combined ranged from 4.7 ng/kg wet weight in reference-site (Baynes Sound) birds to 11.4 ng/kg wet weight in birds from Vancouver Harbour. Nonetheless, elevated EROD activity indicated that birds in Howe Sound were responding to an Ah-receptor-mediated stressor, which was also affecting hematocrit values and possibly vitamin A status. In addition, a low proportion of lymphocytes in individuals across locations in early spring samples was associated with poor body condition. The apparent loss of fitness just prior to the onset of northerly migrations to breeding grounds is of particular concern. Compromised health of mature birds at this point in the season might impact negatively on the productivity and survival of some individuals, particularly those overwintering in Howe Sound.